Desertification, urbanization and population growth have reduced areas which an be used for conventional agriculture. Therefore, agriculture has been increasingly developed in desert or mountain areas, which require effective techniques for watering and fertilizing.
In the past, areas with limited water supply were often treated with anorganic fertilizers and pesticides. Excessive use thereof has led to acidity of soil. Hence stopping degradation and pollution of soil with minimum waste of water has become an important object of agricultural technology.
Conventionally, watering of agricultural plants is performed from a surface of the ground. Water is led via a canal or a pipe to an area to be watered and directly spilled on the ground. Evaporation, seeping and draining away of water, however, result in waste of water.
As an improvement, spraying of water on plants has been used. Therein, a pipe is led to an area to be watered. Water is sprayed into the air above plants, which thereby are watered. As compared to direct spilling of water, efficiency of spraying is higher, but losses due to evaporation are still high, amounting typically to more than 20%. Wind with varying strength and direction adds to waste of water, and spraying on hillsides is not uniform. Furthermore, cost of installing and maintaining pipes, spraying heads and pumps is high.
Conventional watering of plants is therefore wasteful. A further undesired effect thereof is washing out and subsequent sealing of soil surfaces, leading to applied water is not being able to enter soil immediately and being absorbed by soil.
Moreover, conventional watering of plants results in permanently wet soil surfaces, furthering growth of weeds, which in turn consume water and are removed only by costly or environmentally damaging methods, like applying herbicides.
As a response to aforementioned problems, a novel agricultural technique of drip-watering has been developed in Israel, allowing to cultivate trees and other agricultural plants in desert areas. Therein, pipes are laid out in fields, having holes with defined diameters at certain mutual distances, allowing water to drip out at a well-defined rate and at needed locations. Almost no losses by evaporation or seeping away occur, and liquid fertilizer is readily mixed with dripping water to achieve the objects of both watering and fertilizing plants.
However, structural parts required for a conventional drip-watering, a pump, a main pipe, branching pipes, a controlling device, and drip heads, are costly. Furthermore, local differences in water pressure need to be balanced to ensure uniform watering, which is especially important in hillside areas.
Conventional drip watering is performed underground, typically at a depth of about 10 cm. For that purpose, branching pipes are laid underground. Thereby, roots of plants are reached directly by water, so that efficiency is high. However, laying pipes underground and providing for pumps is expensive and not affordable for many common farmers. If negative pressure of supply water is applied, dirt and mood are sucked into the drip heads and pipes, resulting in subsequent failures. Maintenance of conventional drip watering systems is time-consuming and costly.
Conventional fertilizing by anorganic substances like nitrogen, phosphates or potash helps to increase agricultural production, but kills useful microorganisms and earthworms and contributes to sealing of soil.
If fertilizer is applied to the ground surface or upper layers of soil, deeper layers of soil are not fertilized. Consequently, growth of roots concentrates on upper layers of soil, typically up to a depth of 20 cm. Deeper roots do not sufficiently develop, so that natural retrieving of water from deeper ground is not achieved, as is important in dry areas like deserts.